fix: Add Sec-WebSocket-Key and Sec-WebSocket-Version headers when proxying WebSocket from HTTP/2 to HTTP/1

[ZJfans]

Partially fixes #38645

Commit Message:
Implement addition of Sec-WebSocket-Key and Sec-WebSocket-Version headers when Envoy proxies WebSocket requests from HTTP/2 to HTTP/1.
Ensure proper WebSocket upgrade headers are added in compliance with RFC 6455 during HTTP/2 to HTTP/1 proxying.

Note: Sec-WebSocket-Accept header verification is not yet implemented in this PR.

Additional Description:
This PR implements the automatic addition of Sec-WebSocket-Key and Sec-WebSocket-Version request headers when the WebSocket protocol is requested by HTTP/2 client in Envoy and proxied to HTTP/1 backend to comply with RFC 6455 standard.
When the client uses HTTP/2 to make a WebSocket connection with Envoy, Envoy needs to ensure that the WebSocket handshake request contains Sec-WebSocket-Key and Sec-WebSocket-Version request headers when proxied to the HTTP/1 backend. According to RFC 6455, these headers must be included when the client initiates a WebSocket handshake.
Specific implementation:
Sec-WebSocket-Key processing: Envoy will generate a Sec-WebSocket-Key for each WebSocket request and add it to the request header.
Sec-WebSocket-Version processing: Envoy will set Sec-WebSocket-Version to 13, which is the version required by the current WebSocket protocol standard.

Risk Level:
Medium: This functionality involves handling WebSocket headers, which can impact the correctness of WebSocket handshakes. Proper verification and handling are necessary.

Testing:
Manual testing has been conducted in a local environment to verify that Sec-WebSocket-Key and Sec-WebSocket-Version headers are correctly added during the WebSocket handshake from HTTP/2 to HTTP/1.

Automated tests will be added in a follow-up PR to ensure comprehensive coverage and future maintainability.

Docs Changes: None
Release Notes: None
Platform Specific Features: None
[Optional Runtime guard:]
[Optional Fixes #Issue]
[Optional Fixes commit #PR or SHA]
[Optional Deprecated:]
[Optional API Considerations:]

[repokitteh-read-only]

Hi @ZJfans, welcome and thank you for your contribution.

We will try to review your Pull Request as quickly as possible.

In the meantime, please take a look at the contribution guidelines if you have not done so already.

🐱

Caused by: #39375 was opened by ZJfans.

see: more, trace.